Mirrors have been in existence for years and have been used in many applications. Mirrors generally are either (a) first surface mirrors, where the mirror coating is provided between the viewer and the supporting glass substrate, or (b) second surface mirrors, where the supporting glass substrate is interposed between the viewer and the mirror coating. See, for example, U.S. Pat. Nos. 7,276,289 and 7,678,459; U.S. Publication Nos. 2006/0077580; 2007/0178316; 2008/0073203; 2008/0164173; 2010/0229853; 2011/0176212; and 2011/0176236. The entire contents of each of these patent documents are hereby incorporated herein by reference.
Mirrors often require the use of a metallic (Al or Ag) reflective layer. However, it would be desirable if mirrors could be provided without the need for a metallic reflective layer of Al or Ag.
Certain example embodiments of this invention relate to dielectric mirrors and/or methods of making the same. More particularly, certain example embodiments relate to dielectric mirrors having no metallic reflective layer (e.g., no Ag layer and no Al layer) and which are nonetheless capable of realizing film side and/or glass side visible reflection of from about 50-90% (more preferably from about 60-80% and most preferably from about 65-75%) and visible transmission of from about 10-50% (more preferably from about 10-40%, more preferably from about 20-40%, and most preferably from about 25-35%). In certain example embodiments, a layer of or including NiCr or the like, which may be slightly or significantly oxided, may be provided in certain example instances. The dielectric mirrors may be first or second surface mirrors in certain example embodiments, given good performance regarding both glass side reflection and film side reflection. The mirrors may or may not be heat treated (e.g., thermally tempered and/or thermally bent) in certain example embodiments. In certain example instances, such dielectric mirrors may be used in consumer, commercial and/or digital signage applications such as picture frames, bathroom mirrors, TVs, and/or electronic devices.
In certain example embodiments of this invention, there is provided a dielectric mirror including a glass substrate supporting a coating, the coating comprising moving away from the glass substrate: a first transparent dielectric high refractive index layer comprising niobium oxide and/or titanium oxide, the first transparent dielectric high refractive index layer having a thickness of from about 70-140 nm; a second transparent dielectric low refractive index layer comprising silicon oxide, the second transparent dielectric low refractive index layer having a thickness of from about 30-140 nm; a third transparent dielectric high refractive index layer comprising niobium oxide and/or titanium oxide; a fourth transparent dielectric low refractive index layer comprising silicon oxide; a fifth transparent dielectric high refractive index layer comprising niobium oxide and/or titanium oxide; wherein the first transparent dielectric high index layer comprising niobium oxide and/or titanium oxide is at least 10 nm thicker than one or both of (a) the third transparent dielectric high refractive index layer comprising niobium oxide and/or titanium oxide, and/or (b) the fifth transparent dielectric high index layer comprising niobium oxide and/or titanium oxide; wherein the coating does not contain any metallic reflective layer based on Al or Ag; and wherein the dielectric mirror has (i) a film side visible reflectance or a glass side visible reflectance of from about 50-90%, and (ii) a visible transmission of from about 10-40%, and wherein the glass side visible reflectance of the mirror is at least about 30% higher or lower than is the film side visible reflectance of the mirror. The mirror may further comprise a symmetry adjusting layer located between the third transparent dielectric high refractive index layer and the fifth transparent dielectric high refractive index layer. The symmetry adjusting layer may comprise NiCr or the like, and may be at least partially oxided. The symmetry adjusting layer may be located between and contacting the third transparent dielectric high refractive index layer and the fourth transparent dielectric low refractive index layer comprising silicon oxide, or may be located between and contacting the fifth transparent dielectric high refractive index layer and the fourth transparent dielectric low refractive index layer comprising silicon oxide. Instead of using a symmetry adjusting layer, the glass substrate of the mirror may be a grey glass substrate to achieve visible reflectance asymmetry between the film side and glass side of the mirror.
In certain example embodiments of this invention, there is provided a dielectric mirror including a substrate supporting a coating, the coating comprising moving away from the substrate: a first dielectric layer having a refractive index (n) of from about 2.15 to 2.5; a second dielectric layer comprising silicon oxide; a third dielectric layer having a refractive index of from about 2.15 to 2.5; a fourth dielectric layer comprising silicon oxide; a fifth dielectric layer having a refractive index of from about 2.15 to 2.5; wherein the first dielectric layer is at least 20 nm thinner than one or both of the third dielectric layer and/or the fifth dielectric layer; and wherein the coating does not contain any metallic reflective layer.
In certain example embodiments of this invention, there is provided a dielectric mirror including a glass substrate supporting a coating, the coating comprising moving away from the glass substrate: a first transparent dielectric high refractive index layer comprising niobium oxide, the first transparent dielectric high refractive index layer having a thickness of from about 70-140 nm; a second transparent dielectric low refractive index layer comprising silicon oxide, the second transparent dielectric low refractive index layer having a thickness of from about 30-140 nm; a third transparent dielectric high refractive index layer comprising niobium oxide; a fourth transparent dielectric low refractive index layer comprising silicon oxide; a fifth transparent dielectric high index layer comprising niobium oxide; wherein the first transparent dielectric high index layer comprising niobium oxide is at least 10 nm thicker than one or both of the third transparent dielectric high refractive index layer comprising niobium oxide and/or the fifth transparent dielectric high index layer comprising niobium oxide; wherein the coating does not contain any metallic reflective layer; and wherein the dielectric mirror has a visible film side reflectance and/or a visible glass side reflectance of from about 50-90%, and visible transmission of from about 10-40%.
In certain example embodiments of this invention, there is provided a mirror including a substrate (e.g., glass substrate) supporting a coating, the coating comprising moving away from the substrate: a first dielectric layer having a thickness of from about 70-140 nm and a refractive index (n) of from about 2.15 to 2.5; a second dielectric layer comprising silicon oxide; a third dielectric layer having a refractive index of from about 2.15 to 2.5; a fourth dielectric layer comprising silicon oxide; a fifth dielectric layer having a refractive index of from about 2.15 to 2.5; wherein the first dielectric layer is at least 10 nm thicker than one or both of the third dielectric layer and/or the fifth dielectric layer; wherein the coating does not contain any metallic reflective layer; and wherein the mirror has a visible film side reflectance and/or a visible glass side reflectance of from about 50-90%, and visible transmission of from about 20-40%.